With the sound of conflict in the air and their contract set to expire at midnight tonight, members of Broadway’s musicians union voted yesterday to give their president the right to call a strike.

Playing “When the Saints Go Marching In” on drums, trombones, a banjo, trumpet and French horn, about 450 members of Musicians Local 802 marched down Eighth Avenue to protest at the League of American Theaters & Producers’ building on 47th Street.

Union members had already voted 422-15 to give union boss Bill Moriarty the right to make a strike call as they presented 20,000 signatures of support for the musicians union to theater league reps.

The musicians’ contract expires at midnight tonight. They want to maintain a contractual minimum number of players for each show.

Jed Bernstein, president of the producers league, said the vote was a “normal part of any bargaining process.”

The producers are threatening to use recorded music if there is a strike.